It may be desirable to deliver repeated doses of liquid without requiring the recurring inversion of the container. It may also be desirable to provide a dosage system which does not rely solely on gravity for achieving said dosage. It may be particularly desirable to deliver said benefits whilst offering a compact and simple construction. This could be for a number of reasons, including flexibility and ease-of-use offered to the user, ease of manufacture, sustainability and cost effectiveness.
Various solutions exist providing a dosing device of a generally tubular shape, which is suitable to insert into an opening of a container, usually comprising a multiplicity of chambers arranged in such a way to allow fluid communication to occur in separate stages of the pouring maneuver (such as the one described in U.S. Pat. No. 5,129,561). The operation of these devices provides that a dosing chamber is filled up when the container is tilted; the content of said dosing chamber is subsequently transferred into a collecting chamber when the container is tilted back to the upright position; and the content exits the container when the latter is tilted again concurrently with a new dose entering said dosing chamber.
A number of disadvantages are introduced by such an arrangement that will be apparent to the person skilled in the art. For example such arrangement implies a bulky construction, particularly when larger doses are required. Indeed, for any given dose, the volume required for such a mechanism is multiplied by the number of chambers needed. Thus, manufacturing complexity is introduced leading to increased costs and unnecessary materials being used. Furthermore, the user is faced with the inconvenience of a bulky apparatus and the need for repeated tilting of the container for obtaining a dosed amount of liquid.
Other solutions include devices for dispensing measured amounts of liquid in connection with compressible liquid containers (such as those described in U.S. Pat. No. 2,730,270). Such devices usually comprise a collapsible container, a fluid passage conduit extending into said container, and a measuring tube. A dose is generated by squeezing the container in its upright position to allow liquid to flow through the fluid passage conduit and into the measuring tube. Once the measuring tube is filled, the device is tilted to pour the measured content. Finally, the device is tilted back to its upright position to start a new dose.
A disadvantage of such a system is the requirement of repeated tilting of the device between upright and inverted positions for multiple dosage. A further disadvantage is the dependency of the given dose on the volume of the measuring tube, thus introducing limitations as to compactness. Moreover, accuracy of dosage may be affected by any amount of liquid being sucked back into the container via the fluid passage conduit upon release of pressure.
Other devices provide metered doses of liquid from a container wherein the liquid is dispersed by squeezing or by pressurizing said container contents in some other way (such as those described in EP0274256A1). The user tilts the container and squeezes the container thus forming a pressure build up which forces the liquid through liquid outlet openings into a control chamber. In the meantime liquid flows through a small aperture at the bottom of said control chamber to force displacement of a piston towards a liquid outlet tube. Once the piston reaches the outlet tube the flow of liquid is stopped and the dose is complete. Tilting the container back to an upright position allows the piston to slowly return to its original position ready for a subsequent dosage. However, such arrangement still requires tilting the device upside down and upright for each dosage.
An attempt to solve this problem is described in WO 2005/049477. WO 2005/049477 discloses a device for providing metered doses of liquid from a container wherein the liquid is dispensed by squeezing of a container. The device disclosed comprises a dump valve arrangement provided at the back of a control chamber to allow rapid escape of liquid from the control chamber behind an obturator after a dose has been dispensed, to speed the return of the obturator to its rearward (starting) position. The dump valve closes during dispensing, under gravity or forward fluid pressure, and opens after dispensing, under gravity or reverse fluid pressure. However, such arrangement introduces disadvantages such as increased number of parts and jamming of the obturator following discharge of the liquid caused by left-behind residue accumulating at the bottom of the control chamber that subsequently dries up. This in turn may affect the consistency of the dosage.
Thus, there still remains a need for a simple, cost effective, efficient in use and compact apparatus and means of repeatedly dispensing controlled doses of liquid with improved drainage of the dosing chamber. There also remains a need for such devices having larger dose flexibility, improved dosing accuracy and dosing speed and consistency even at low squeeze forces.
It has been found that the apparatus of the present invention achieves a substantially constant liquid output which can be achieved substantially independently from pressure fluctuations caused by variations in the squeezing force and the fill level of the container during use.
A further advantage of the present invention is that substantially constant dosage is achieved even when close to product depletion.
Other objects, features and advantages of the invention will be better understood with reference to the attached drawings and the specification hereinafter.